Hello Stewart,
Three years ago
Stocktake, the "viz whizz", put me on to a supply of motors from China via eBay. I've just checked and the item number is still listed but the seller has changed the motor to a lower voltage so that won't be any good. Send a PM to Dave as if anyone can help, he will be able to.
The relay you want is from the Tyco V23079 series (DPDT non-latching, PCB mounted, 5A max, switching current 2A, 12v DC) which was available from RS under part no. 256-0655 (but admittedly that was 12 years ago). The good news is that it's still available at £4.03 each, probably plus VAT.
Simon